By CARYN JAMES

efore settling on David Copperfield as the name of his most autobiographical hero, Dickens called the character Thomas Mag, and the novel ''Mag's Diversions.''
The name resurfaced, slightly changed, for the convict Magwitch in ''Great Expectations,'' and proved a better fit. In the 19th century ''to magg'' meant ''to pilfer,'' and Magwitch,
the thief who gave Pip his expectations, was surely a scoundrel turned magician.

All these allusions and dozens more resonate through ''Jack Maggs,'' Peter Carey's wondrous, sly, Dickensian swirl of a novel. Though its hero claims that he got his name because his foster mother thought he chattered like a magpie,
there is more than chatter going on here. In ''Jack Maggs,'' Carey creates a rousing old-fashioned narrative, and brings to it a distinctly modern, unromantic sensibility.

This is a strangely enticing combination, and it has become the hallmark of Carey's best work, informing such wildly different novels as ''Oscar and Lucinda'' (an antiromantic 19th-century romance) and ''The Unusual
Life of Tristan Smith'' (a bleak, futuristic fantasy that owes much to the 18th-century ''Tristram Shandy''). In ''Jack Maggs,'' the bright 19th-century surface masks a world-weary 20th-century
heart. The novel transforms Dickens's characters and his London into a fable about class, national identity and art: contemporary subjects dear to Carey, an Australian living in New York.

The most alluring quality of ''Jack Maggs'' is also the simplest. With its great forward rush of a narrative, the novel stands on its own as an adventure story, and can be read without reference to ''Great Expectations.''
It's more fun, though, to catch the way ''Jack Maggs'' glints off Dickens's work and life.

In 1837, Jack Maggs, a convict transported to Australia, illegally returns to London, facing death if he is caught. He is determined to visit Henry Phipps, the boy he once spotted in a blacksmith's forge and whom he turned into a gentleman with the
fortune he earned in New South Wales. The quest for Phipps comes to involve hypnotism, skirmishes with the police, even murder.

From the start, Carey takes a Dickensian relish in details. Maggs wears a red waistcoat and carries a silver-tipped cane. He has a hawklike nose and two fingers missing from his left hand. And after 24 years away, he finds London much altered. ''There
was now a tobacconist in Great Queen Street,'' Carey writes, ''and a narrow little workroom where glass eyes were made for dolls and injured gentlemen.'' The gentlemen themselves have changed, for Phipps is
not the only newly minted member of the gentry in this London of suddenly fluid classes. Finding Phipps's house empty, Maggs becomes a footman in the house next door, owned by a onetime fishseller named Percy Buckle, who has received
a fortune from a benefactor of his own.

The Buckle household is replete with bizarre comic characters, beginning with the housekeeper who measures Maggs to be sure his height matches that of the other footman. There is also Mercy Larkin, a young housemaid Buckle has saved from ruin on the streets.
And, most important, there is a visitor, a writer named Tobias Oates, who suspiciously resembles the young Charles Dickens.

It has become common for audacious or self-deluded writers to fill in the gaps of great novels. Everyone from Austen to Hawthorne to Wharton has received this treatment lately, usually with shabby results. Carey is up to something more sophisticated,
and his relation to Dickens's work is playfully skewed. We quickly see that Jack Maggs is not quite Abel Magwitch, though they have those Australian interludes in common; for one thing, Maggs is 20 years younger. Henry Phipps is not
Pip; in a typically cynical Carey touch, Phipps is selfish and debauched, totally unworthy of his inheritance.

And the character of Oates raises a mischievous question: how much does this monstrously self-absorbed writer reflect Dickens? Like Dickens, Oates is a debt-ridden author who churns out articles for The Morning Chronicle, and has risen above his class.
When Carey says that Oates resembles ''the portrait Samuel Lawrence painted of him in 1838,'' he is describing a famous drawing of Dickens. And, like Dickens, Oates is fascinated by mesmerism, hypnotizing Maggs as Dickens
did his friends. Oates pilfers Maggs's life and turns it into fiction. But the excerpts we read from his work suggest nothing of Dickens's genius. As a journalist, Oates is a hack; as a novelist, second-rate.

Carey is not rewriting Dickens here but taking us behind the curtain of Dickens's creation. ''Jack Maggs'' stands in relation to ''Great Expectations'' as ''Great Expectations'' itself stands
in relation to Dickens's life: it is a fictional extrapolation in which ''real'' events and sources are merely glimpsed; they have been transformed into something fresh, which defies one-to-one correspondences.

This novel's vision of Maggs begins where Pip's view of Magwitch ends: with sympathy for the convict, though not for his wrongheaded attitude about the value of being a gentleman. Carey reveals Maggs's history using two clever devices.
Interspersed through the novel are letters from Maggs to Phipps, written, we are told, in backward script with purple vanishing ink. Phipps will need a mirror and lemon juice to read them. These vivid letters show Maggs to be a victim
of his own Dickensian childhood, which echoes ''Oliver Twist.'' As an infant, he was taken in by a harsh woman named Mary Britten, who raised him for a secret purpose. At 6, the baffled child was sent down a chimney
to rob a rich man's house, and so entered his life of crime.

Maggs is understandably reluctant to reveal his adult history, but Oates learns of it accidentally when he uses mesmerism to stop an excruciating pain in Maggs's face. In Maggs's story, Oates sees a career opportunity. ''It's
the Criminal Mind,'' he says, ''awaiting its first cartographer,'' and he persuades Maggs to continue being mesmerized in exchange for help in finding Phipps.

Though noted for cartoonish characters such as Captain Crumley and Mrs. Moorefallen, Oates is a writer obsessed with what he fears. ''He feared poverty; he wrote passionately about the poor. He had nightmares about hanging; he sought out executions,
reporting them with a magistrate's detachment.'' Carey extends some sympathetic understanding to Oates here, even while the scenes of Maggs's hypnosis capture the insidious way the writer victimizes his subject.

And if Oates exploits Maggs, he uses the women in his life even more brutally, under the guise of love. Early on, we learn that Oates is having an affair with his wife's 18-year-old sister, Lizzie, who is part of the Oates household. Lizzie combines
elements of two of Dickens's sisters-in-law: when Mary Hogarth, who lived with the family, died at 17, Dickens plunged into inappropriately dramatic grief; years later, when Dickens's wife, Kate, left him, his relationship with
Georgina Hogarth provoked such speculation that he issued a public denial. (In fact, he was in love with the young actress Ellen Ternan; he denied that, too.)

Carey turns these rumors from Dickens's life into the harsh facts of Oates's. He undermines the romantic image of Dickens as kindly and fatherly, an image that persists today despite detailed knowledge of his selfishness. Along the way, Carey
raises larger questions about how writers prey on the lives of others. Passion takes his people where Dickens's were not allowed to go. There are minor but blunt references to homosexuality. And when at one point characters in ''Jack
Maggs'' cross paths, thanks to wild Dickensian coincidences, those crossed paths involve abortion.

Maggs, with his starry-eyed ideas about what it means to be an Englishman, turns out to be the book's most romantic character. In recent Australian newspaper interviews, Carey has said that he thought of Maggs as ''my imaginary ancestor.''
But the novel's attempt to depict him as a founding father of the modern Australian character develops late and is not especially convincing.

What convinces thoroughly is the depiction of how Maggs has been brain-washed by centuries of upper-class English propaganda. Making Phipps a gentleman brings Maggs closer to what he considers his true and ideal home, ''a house in Kensington
whose kind and beautiful interior he had entered by tumbling down a chimney.'' Maggs's foster mother, whom he always calls Ma Britten, embodies a brutal portrait of Mother England: she is an abortionist who rises to acquire
the household trappings of a gentlewoman.

''Jack Maggs'' is the fourth in a string of astonishing novels by Carey. In his earliest work -- the story collection ''The Fat Man in History'' and the novels ''Bliss'' and ''Illywhacker''
-- his cultural themes are in place but seem to float above the characters. And he had not yet learned to offset bitterness with humanity. Despite their ambition, these works seem emotionally small.

But in 1988, he took a huge leap forward with ''Oscar and Lucinda.'' The perfect love between the book's English clergyman and Australian heiress is so misbegotten they cannot even declare it, much less live happily ever after.
Yet the novel is so rich with life that its jubilant tone tempers the underlying sad realism. Similarly, there is a life-affirming birth at the end of ''The Tax Inspector'' though the title character delivers her child
in a dank, filthy basement where she is held captive by a member of the comically grotesque Catchprice family. And the hero of ''Tristan Smith'' creates a good life despite the fact that he was born without lips.

Carey's invention and uncompromising fidelity to character are sustained almost to the finish of ''Jack Maggs.'' Surprisingly, the ending carries a heavy load of Dickensian sentimentality. You can't argue that this ending
parodies Dickens, because nothing else in the novel does. Instead, it seems rigged by Carey to reinforce Maggs's Australian identity.

But that is a minor disappointment. The ending never falters in its wily creation of a parallel Dickensian universe. We learn that Oates's fabulously successful novel ''The Death of Maggs'' began appearing in serial form in 1860.
Its competition would have been ''Great Expectations.''

Caryn James is chief television critic of The Times. Her first novel, ''Glorie,'' will be published in May.